Biofabricating Three-Dimensional Bacterial Cellulose Composites Using Waste-Derived Scaffolds

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This study explores a new method of developing low-emission, resource-efficient materials based on BC using waste streams, emphasising recyclability and biodegradability to support circular economies. The value of this work is high and the paper is prepared well. However, there are still some problems that must be carefully revised. Generally, I recommend its acceptance after minor revision and highlighting novelty.

1. The introduction is general. It is suggested to  review the existing methods and further refine the introduction.
2. In Line 231~233, is there any correlation between the hydrophilic and hydrophobic properties of the fibers and the content displayed in SEM? It is not explained clearly here.
3. In Line245, I cannot find spherical agglomerations in Figure 6. It's best to mark it in SEM.

 

Author Response

We thank the reviewers for their careful review of our manuscript. We have addressed these comments in detail and revised the manuscript accordingly. All the changes are highlighted in the manuscript (using track changes); and individual responses to reviewers’ comments are bellow. We believe that these changes has improved the manuscript and made it suitable for publication:
Reviewer 1:
Comments and Suggestions for Authors
This study explores a new method of developing low-emission, resource-efficient materials based on BC using waste streams, emphasising recyclability and biodegradability to support circular economies. The value of this work is high and the paper is prepared well. However, there are still some problems that must be carefully revised. Generally, I recommend its acceptance after minor revision and highlighting novelty.
We thank the reviewer for highlighting the novelty of our manuscript as our main aim is to release this work in the open access publication and hopefully develop interest and further research in this exciting research area.
1. The introduction is general. It is suggested to review the existing methods and further refine the introduction.

Thank you for the comments; we agree the reviewer and have now updated the introduction to better represent the main aim of this research work, the changes are highlighted in the manuscript (track changes) and new references has also been added to ensure the literature review is up to date.
2. In Line 231~233, is there any correlation between the hydrophilic and hydrophobic properties of the fibers and the content displayed in SEM? It is not explained clearly here.

Thank you, the explanation around the hydrophobicity of wool fibres and hydrophilic membrane surrounding the fibres has been updated with added reference.
3. In Line245, I cannot find spherical agglomerations in Figure 6. It's best to mark it in SEM.

We have now highlighted some of these agglomerates in the figure and removed the word spherical to make the Figure more clear for the reader.

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript titled “Biofabricating Three-Dimensional Bacterial Cellulose Composites using Waste-Derived Scaffolds” by Kniep, J.; et al. is a scientific work where the authors assessed the positive impact of bacterial cellulose from symbiotic cultures of bacteria and yeast on wool and cotton textile samples at their end-life. The most relevant outcomes found in this research could serve to pave the way in the design of the next-generation of materials for energy storage, food packaging, among other Industry applications. The manuscript is generally well-written and this is a topic of growing interest.

However, it exists some points that need to be addressed (please, see them below detailed point-by-point) to improve the scientific quality of the submitted manuscript paper before this article will be consider for its publication in Applied Sciences.

1) Keywords. The authors should consider to add the term “symbiotic culture of bacteria and yeast” in the keyword list.

 

 

2) Introduction. The Abstract section mentioned the potential applications of this research in biomedical, energy storage or filtration. Could the authors provide quantitative data insights according to the worldwide economic impact of the above described Industry manufacturing sectors? This will significantly aid the potential readers to better understand the significance of this devoted research.

 

3) “It has been shown that the metabolism of microorganisms (…) Bacterial Cellulose (…) stronger than steel at the nanosale (…) due to its highly polymerised and crystalline structure (…)” (lines 38-43). Here, even if I agree with this statement furnished by the authors, it would be neccesary to discuss how nanocrystalline cellulose is not only mechanically stronger but also resistant to the environmental moisture [1] leading to materials with enhanced properties [2].

[1] https://doi.org/10.1016/j.ijbiomac.2019.10.074

[2] https://doi.org/10.1016/j.carpta.2023.100391

 

4) Materials & Methods. “To create the scaffolds, textile samples (sheep wool felt and cotton fabric) (…) to suspend the scaffolds in 50 mL Falcon tubes (…)” (lines 126-127). Are all the examined textile samples coming from the same source? In case negative, how the chemical treatment and textile coloration with dyes could affect to the data interpretation?

 

5) “2.3 Visual analysis” (lines 165-177). What was the electron acceleration voltage rate to gather the SEM images?

 

6) Results. Did the authors test different media to growth the symbiotic culture of bacteria and yeast to optimize in what are the most efficient conditions?

 

7) “Optical microscopy (…) (see Error! Reference source not found.)” (lines 187-190). The bibliography manager tool experienced an issue. The authors should fix it and this comment taken into account for the rest of the main manuscript body text.

 

8) Figure 3 (line 212). A statistical analysis should be conducted in order to discern if the observed differences among the examined conditions are statistically significant.

 

9) Finally, a chemical analysis monitoring the modifications experiences during the 6 weeks would also benefit this research and will serve to have a more complete outlook of the action mechanisms of SCOBY on the wool and cotton samples.

 

10) “5. Conclusions” (lines 366-386). This section perfectly remarks the most relevant outcomes found by the authors in this work and also the promising future prospectives. It may be desirable to add a brief statement to discuss about the future action lines to pursue the topic covered in this research.

Author Response

We thank the reviewers for their careful review of our manuscript. We have addressed these comments in detail and revised the manuscript accordingly. All the changes are highlighted in the manuscript (using track changes); and individual responses to reviewers’ comments are bellow. We believe that these changes has improved the manuscript and made it suitable for publication:

Comments and Suggestions for Authors

The manuscript titled “Biofabricating Three-Dimensional Bacterial Cellulose Composites using Waste-Derived Scaffolds” by Kniep, J.; et al. is a scientific work where the authors assessed the positive impact of bacterial cellulose from symbiotic cultures of bacteria and yeast on wool and cotton textile samples at their end-life. The most relevant outcomes found in this research could serve to pave the way in the design of the next-generation of materials for energy storage, food packaging, among other Industry applications. The manuscript is generally well-written and this is a topic of growing interest.

We thank the reviewer for careful review and highlighting the main point of this manuscript which is to pave the way in the design of novel next generation biomaterials.

However, it exists some points that need to be addressed (please, see them below detailed point-by-point) to improve the scientific quality of the submitted manuscript paper before this article will be consider for its publication in Applied Sciences.

• The authors should consider to add the term “symbiotic culture of bacteria and yeast” in the keyword list.
  Thank you, this is now added to the keywords.
• The Abstract section mentioned the potential applications of this research in biomedical, energy storage or filtration. Could the authors provide quantitative data insights according to the worldwide economic impact of the above described Industry manufacturing sectors? This will significantly aid the potential readers to better understand the significance of this devoted research.
  We have improved our introduction by making it more focused on the subject matter and removed some of the unnecessary text. This has now made the abstract and introduction more understandable and focused and the specific description of the manufacturing sectors in the abstract has now been removed.
• “It has been shown that the metabolism of microorganisms (…) Bacterial Cellulose (…) stronger than steel at the nanosale (…) due to its highly polymerised and crystalline structure (…)” (lines 38-43). Here, even if I agree with this statement furnished by the authors, it would be neccesary to discuss how nanocrystalline cellulose is not only mechanically stronger but also resistant to the environmental moisture [1] leading to materials with enhanced properties [2].
  10. [1] https://doi.org/10.1016/j.ijbiomac.2019.10.074
  11. [2] https://doi.org/10.1016/j.carpta.2023.100391
      Thank you for this comment, we have now added and updated this section of the introduction, and have added the suggested references to the introduction.

 

• Materials & Methods. “To create the scaffolds, textile samples (sheep wool felt and cotton fabric) (…) to suspend the scaffolds in 50 mL Falcon tubes (…)” (lines 126-127). Are all the examined textile samples coming from the same source? In case negative, how the chemical treatment and textile coloration with dyes could affect to the data interpretation?
  Thank you; this is an important question and would need further investigation to address if different chemical treatments and colouring of the textile fibres would have an effect on the growth and arrangements of the cellulose membrane. However, for the sake of this study we have used the same cotton fabric throughout all the experiments as well as the same sheep wool waste source. There is no difference between the fabric and wool scaffolds throughout this paper and we believe that this is a valid point that needs to be studied further and can be one of the future steps in this study.  
• “2.3 Visual analysis” (lines 165-177). What was the electron acceleration voltage rate to gather the SEM images?
  The materials and methods on SEM work has been updated with the relevant information.
• Did the authors test different media to growth the symbiotic culture of bacteria and yeast to optimize in what are the most efficient conditions?
  For this study we performed a detailed literature research and used the most optimal conditions from the available literature. The methods were selected to show the most common practices for growing SCOBY considering most repeatable conditions using readily available material.
• “Optical microscopy (…) (see Error! Reference source not found.)” (lines 187-190). The bibliography manager tool experienced an issue. The authors should fix it and this comment taken into account for the rest of the main manuscript body text.
  The references has been checked and turned into text to avoid Error messages.
• Figure 3 (line 212). A statistical analysis should be conducted in order to discern if the observed differences among the examined conditions are statistically significant.
  The statistical analysis is performed and added to the relevant figure and in the materials and methods.
• Finally, a chemical analysis monitoring the modifications experiences during the 6 weeks would also benefit this research and will serve to have a more complete outlook of the action mechanisms of SCOBY on the wool and cotton samples.
  As the main aim of this study was a proof of concept for vertical growth of SCOBY, we haven’t performed chemical analysis on the resulting SCOBY but this is an important factors that we will be considering in future work.
• “5. Conclusions” (lines 366-386). This section perfectly remarks the most relevant outcomes found by the authors in this work and also the promising future prospectives. It may be desirable to add a brief statement to discuss about the future action lines to pursue the topic covered in this research.
  Thank you; we have now added some sentences at the end to reflect some of the future directions that can be considered.

 

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors did a great deal of effort to cover all the suggestions raised by the Reviewers. For this reason, the scientific manuscript quality was greatly improved. Based on the novelty and significance of the gathered results, I warmly endorse this work for further publication in Applied Sciences.

Author Response

We thank the reviewer for the kind comments and agree that the changes according to the reviewers suggestions has greatly improved the manuscript.